Weather and climate in Philadelphia (Pennsylvania)

The climate of Philadelphia is continental, with cold winters and hot summers. Philadelphia is the largest city of Pennsylvania, and is located halfway between New York and Washington, and about 90 km (55 miles) from the Atlantic coast. The climate is similar to that of New York, however, being a little further away from the sea, it is a little less rainy than New York (and less snowy in winter), and a bit warmer in summer as well.
The daily average temperature ranges from 1.3 °C (34.3 °F) in January to 25.6 °C (78 °F) in July. Here are the average temperatures.

The city is located in an area where different air masses collide: the cold ones coming from Canada and the warm ones coming from the Gulf of Mexico. The result is an unstable climate, with waves of bad weather alternating with clear and sunny days. The wind blows frequently as well.
Precipitation is quite abundant: in one year, more than 1,100 millimeters (43 inches) of rain fall. Here is the average precipitation.

Winter, from December to February, is cold: the average temperature is just above freezing (0 °C or 32 °F), but cold spells, during which the temperature can drop to about -10/-15 °C (5/14 °F), are not rare. The wind chill can make the air feel colder than it actually is.
The coldest record is -21 °C (-6 °F) and was set in January 1982 and in January 1985.
Snowfalls are frequent, and sometimes can be abundant, resulting in real snowstorms. The heaviest snowfall in a single day occurred on January 7, 1996, when 70 centimeters (27.5 inches) of snow fell. On average, 59 centimeters (23 inches) of snow fall annually.
On other occasions, the wind can blow from the south, bringing some mild days, with highs around 12/15 °C (54/59 °F). There are also clear and sunny days, with cold nights, and daytime temperatures mild or in any case acceptable.

In spring, from March to May, the weather continues to be unstable: the first warm days alternate with the return of cold weather. In March, it can snow, and this can sometimes happen still in early April. But already in April, the temperature can sometimes exceed 25 °C (77 °F). By May, the average temperature becomes pleasant, although there can still be cool days, or even a little cold and rainy, while the first heat waves can bring the temperature above 30 °C (86 °F). On sunny days, the first afternoon thunderstorms can erupt.

Summer, from June to August, is hot and humid, especially in July and August. There can be days with pleasant temperatures, around 25/27 °C (77/81 °F), maybe with some rain, but more often, there are hot and sultry days, with highs around 30 °C (86 °F). On sunny days, thunderstorms can occur in the afternoon.
Sometimes, even heat waves occur, when the temperature reaches 36/38 °C (97/100 °F), and remains high at night, around 25 °C (77 °F) or above. The highest record is 40.6 °C (105.1 °F) and was set in July 2011.

Autumn, from September to November, is milder and less unstable than the other seasons, at least in the first part. In early September, the weather is often still characterized by heat and humidity, with sunshine and some afternoon thunderstorms, then it quickly becomes mild and relatively quiet until mid-October, while in the second half of October, the first cold days may occur. November is by now a cold month, during which the first snowfalls may occur. There is a moderate amount of rainfall also in autumn, but it is still the season in which rainy days are a little less frequent.



The amount of sunshine in Philadelphia is good in summer, but it's not low even in winter because, as mentioned, some sunny days can always occur. Here are the average sunshine hours per day.

The sea at Long Beach on the Atlantic to the coast east of Philadelphia (see Atlantic City, Ocean City, Avalon) is not very warm, however, it can be considered as warm enough for swimming in July and August, when the water temperature reaches 22/23 °C (72/73 °F), while it becomes definitely cold in winter. Here are the average sea temperatures near Atlantic City.

Best Time

The best times to visit Philadelphia are spring and autumn, in order to avoid both the winter cold and the summer heat, and in particular, the month of May and from mid-September to mid-October. June is often a good month as well, but sometimes it can be hot. In early September, the weather can be sticky, though not as hot as in midsummer. In April, it can sometimes be cold and the weather can be unstable, especially at the beginning of the month, while the second half of the month is usually mild.

Philadelphia - Weather by month

Based on the period 1991-2020

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January, the coldest month of the year, is generally a cold month. The average temperature is of 1.3 °C (34 °F), with a minimum of -3.3 °C (26 °F) and a maximum of 5.8 °C (42.5 °F).
On the coldest nights of the month, the temperature usually drops to around -12.5 °C (9.5 °F). However, it dropped to -20.6 °C (-5.1 °F) in January 1994.
On the warmest days of the month, the temperature usually reaches around 17.5 °C (64 °F). However, it reached 23 °C (73.4 °F) in January 2007.
Precipitation amounts to 80 mm (3.1 in), distributed over 11 days.
The day lasts on average 9 hours and 40 minutes.
There are on average 5 hours of sunshine per day. So, the sun shines 52% of the time.
The average humidity is 63%.
The average wind speed is 14 kph (9 mph).

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February is generally a cold month. The average temperature is of 2.4 °C (36 °F), with a minimum of -2.7 °C (27.1 °F) and a maximum of 7.6 °C (45.7 °F).
On the coldest nights of the month, the temperature usually drops to around -11 °C (12 °F). However, it dropped to -16.7 °C (1.9 °F) in February 2015.
On the warmest days of the month, the temperature usually reaches around 17.5 °C (63.5 °F). However, it reached 26.1 °C (79 °F) in February 2018.
Precipitation amounts to 70 mm (2.8 in), distributed over 10 days.
The day lasts on average 10 hours and 40 minutes.
There are on average 5.5 hours of sunshine per day. So, the sun shines 52% of the time.
The average humidity is 60%.
The average wind speed is 15 kph (9 mph).

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March is generally a quite cold month. The average temperature is of 6.5 °C (44 °F), with a minimum of 0.9 °C (33.6 °F) and a maximum of 12.1 °C (53.7 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around -7 °C (19 °F). However, it dropped to -12.8 °C (9 °F) in March 2015.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 23 °C (73.5 °F). However, it reached 31.1 °C (88 °F) in March 1998.
Precipitation amounts to 100 mm (3.9 in), distributed over 11 days.
The day lasts on average 12 hours and 0 minutes.
There are on average 6.5 hours of sunshine per day. So, the sun shines 55% of the time.
The average humidity is 58%.
The average wind speed is 15 kph (10 mph).

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April is generally a mild month. The average temperature is of 12.5 °C (54 °F), with a minimum of 6.3 °C (43.3 °F) and a maximum of 18.7 °C (65.7 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around -0.5 °C (30.5 °F). However, it dropped to -4.5 °C (23.9 °F) in April 1995.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 29 °C (84 °F). However, it reached 34 °C (93.2 °F) in April 2002.
Precipitation amounts to 90 mm (3.5 in), distributed over 11 days.
The day lasts on average 13 hours and 20 minutes.
There are on average 7 hours of sunshine per day. So, the sun shines 54% of the time.
The average humidity is 57%.
The average wind speed is 15 kph (9 mph).

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May is generally a very mild month. The average temperature is of 17.9 °C (64 °F), with a minimum of 11.8 °C (53.2 °F) and a maximum of 24.1 °C (75.4 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 4.5 °C (40 °F). However, it dropped to 1.6 °C (34.9 °F) in May 1996.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 32 °C (89.5 °F). However, it reached 35 °C (95 °F) in May 1991.
Precipitation amounts to 85 mm (3.3 in), distributed over 11 days.
The day lasts on average 14 hours and 25 minutes. So the days are long.
There are on average 8 hours of sunshine per day. So, the sun shines 55% of the time.
The average humidity is 63%.
The average wind speed is 12 kph (8 mph).

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June is generally a warm to hot month. The average temperature is of 22.8 °C (73 °F), with a minimum of 17 °C (62.5 °F) and a maximum of 28.6 °C (83.6 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 10 °C (50 °F). However, it dropped to 6.7 °C (44.1 °F) in June 1992.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 34.5 °C (94.5 °F). However, it reached 37.2 °C (99 °F) in June 2008.
Precipitation amounts to 105 mm (4.1 in), distributed over 10 days.
The day lasts on average 15 hours and 0 minutes. So the days are long. June 21, the summer solstice, is the longest day of the year in the Northern Hemisphere.
There are on average 9 hours of sunshine per day. So, the sun shines 60% of the time.
The average humidity is 64%.
The average wind speed is 12 kph (7 mph).

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July, the hottest month of the year, is generally a warm to hot month. The average temperature is of 25.6 °C (78 °F), with a minimum of 20 °C (68.1 °F) and a maximum of 31.2 °C (88.1 °F).
On the coldest nights of the month, the temperature usually drops to around 15 °C (59 °F). However, it dropped to 12 °C (53.6 °F) in July 1997.
On the warmest days of the month, the temperature usually reaches around 36.5 °C (97.5 °F). However, it reached 40.6 °C (105.1 °F) in July 2011.
Precipitation amounts to 110 mm (4.3 in), distributed over 10 days.
The day lasts on average 14 hours and 40 minutes. So the days are long.
There are on average 9 hours of sunshine per day. So, the sun shines 61% of the time.
The average humidity is 64%.
The average wind speed is 11 kph (7 mph).

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August is generally a warm to hot month. The average temperature is of 24.6 °C (76 °F), with a minimum of 19.1 °C (66.4 °F) and a maximum of 30.1 °C (86.1 °F).
On the coldest nights of the month, the temperature usually drops to around 14 °C (57 °F). However, it dropped to 11.6 °C (52.9 °F) in August 1992.
On the warmest days of the month, the temperature usually reaches around 35 °C (95 °F). However, it reached 39.4 °C (102.9 °F) in August 2001.
Precipitation amounts to 110 mm (4.3 in), distributed over 9 days.
The day lasts on average 13 hours and 40 minutes.
There are on average 8.5 hours of sunshine per day. So, the sun shines 61% of the time.
The average humidity is 67%.
The average wind speed is 10 kph (6 mph).

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September is generally a warm month. The average temperature is of 20.8 °C (69 °F), with a minimum of 15.2 °C (59.3 °F) and a maximum of 26.4 °C (79.5 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around 7 °C (44.5 °F). However, it dropped to 5 °C (41 °F) in September 2000.
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 32.5 °C (91 °F). However, it reached 36.1 °C (97 °F) in September 1993.
Precipitation amounts to 110 mm (4.3 in), distributed over 9 days.
The day lasts on average 12 hours and 25 minutes.
There are on average 7.5 hours of sunshine per day. So, the sun shines 59% of the time.
The average humidity is 68%.
The average wind speed is 11 kph (7 mph).

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October is generally a mild month. The average temperature is of 14.4 °C (58 °F), with a minimum of 8.7 °C (47.6 °F) and a maximum of 20.1 °C (68.2 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around 1 °C (34 °F). However, it dropped to -1.1 °C (30 °F) in October 2001.
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 28 °C (82.5 °F). However, it reached 35.6 °C (96.1 °F) in October 2019.
Precipitation amounts to 90 mm (3.5 in), distributed over 9 days.
The day lasts on average 11 hours and 5 minutes.
There are on average 6.5 hours of sunshine per day. So, the sun shines 60% of the time.
The average humidity is 68%.
The average wind speed is 11 kph (7 mph).

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November is generally a mild month. The average temperature is of 8.6 °C (47 °F), with a minimum of 3.3 °C (37.9 °F) and a maximum of 13.9 °C (57.1 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around -4.5 °C (24 °F). However, it dropped to -8.9 °C (16 °F) in November 2018.
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 23 °C (73.5 °F). However, it reached 27.2 °C (81 °F) in November 1993.
Precipitation amounts to 75 mm (3 in), distributed over 9 days.
The day lasts on average 10 hours and 0 minutes.
There are on average 5 hours of sunshine per day. So, the sun shines 52% of the time.
The average humidity is 64%.
The average wind speed is 12 kph (8 mph).

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December is generally a cold month. The average temperature is of 3.9 °C (39 °F), with a minimum of -0.6 °C (30.8 °F) and a maximum of 8.5 °C (47.3 °F).
On the coldest nights of the month, the temperature usually drops to around -8.5 °C (17 °F). However, it dropped to -13 °C (8.6 °F) in December 2004.
On the warmest days of the month, the temperature usually reaches around 18.5 °C (65.5 °F). However, it reached 25 °C (77 °F) in December 1998.
Precipitation amounts to 100 mm (3.9 in), distributed over 11 days.
The day lasts on average 9 hours and 25 minutes. December 21, the winter solstice, is the shortest day of the year in the Northern Hemisphere.
There are on average 4.5 hours of sunshine per day. So, the sun shines 47% of the time.
The average humidity is 65%.
The average wind speed is 13 kph (8 mph).